rgw: fix multi instances scaleout

rgw: fix multi instances scaleout

When rgw and osd are collocated, the current workflow prevents from
scaling out the radosgw_num_instances parameter when rerunning the
playbook.

The environment file used in the rgw systemd template is rendered when
executing the `ceph-rgw` role but during a new run of the playbook (in
order to scale out rgw instances), handlers are triggered from `ceph-osd`
role which is run before `ceph-rgw`, therefore it tries to start the new
rgw daemon whereas its corresponding environment file hasn't been
rendered yet and fails like following:

```
ceph-radosgw@rgw.ceph4osd3.rgw1.service failed to run 'start-pre' task: No such file or directory
```

This commit moves the tasks generating this file in `ceph-config` role
so it is generated early.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1851906
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit 7dd68b9ac1086e3c15cfad3812f1c141eadd80c0)